The study proposes to (1) define a population at increased risk for celiac disease (CD) by expression of HLA susceptibility genes, and measure endomysial antigen (EMA) in 3/4 genotype children, 4/4 genotype controls, 3/x genotype children, first-degree relatives of CD patients, and insulin-dependent diabetes mellitus patients; (2) biopsy the small bowel in 70 predicted EMA children; (3) characterize associated environmental exposures; and (4) test for non-HLA-DR/DQ susceptibility genes.